surfacegrafted europium and erbium complexes of the 12tungstosilicate heteropolyoxometalate: a synthetic and structural investigations

The hydrothermal synthesis of two new inorganicorganic hybrid materials in which pda (pda = 1,10phenanthroline2,9dicarboxylate) is connected to a welldefined keggintype polyoxometalate anion (pom) and a ln(iii) cation (pom = [siw12o40]4−; ln = eu3+ (1), er3+ (2)), are reported. these hybrids are characterized by elemental analyses, ir spectra and singlecrystal xray diffraction. singlecrystal xray analysis reveals that both compounds have been assembled by hydrogen bonding and anionπ interactions among pom, pda and lattice water units into a threedimensional (3d) supramolecular structure. compound 1 is composed of two different cationic layers of eu(iii) clusters with the poms located in cavities that are created by the eupda groups. compound 2 consists of [siw12o40]4– keggintype poms, where a single {w3o13} triad is decorated by a trinuclear er(iii)complex.